Electric contact ring for knitting machines



May 13, 1941;

M. WACHSMAN 2,241,683 ELECTRIC C ONTACT RING FOR KNITTING MACHINES FiledApril 6, 1940 E E %I/%/Z447INVENTOR 70W dim 6.

Patented May 13, 1941 ELECTRIC CONTACT RING FOR KNITTING MACHINESMichael Wachsman,

Wachsman Sons, Inc., a

York

Application April 6,

\2 Claims.

This invention relates to electric contact rings which are used inknitting machines for conducting electric current to certain parts ofthe machine. More particularly such rings are used to provide electriccontact for so called slack take up devices or end detectors in which awire arm is held in a normal open circuit position by the travellingyarn. When the yarn breaks or runs out the arm moves into contact withthe ring to close the electric circuit which then in known manner causesthe knitting machine to stop so the trouble with the yarn can beattended to. The electric circuit is normally open to avoid shocks tothe operator. Such contact rings are shown for instance in the U. S.Patents No. 2,147,275, Feb. 14, 1939, and No. 2,168,755, Aug. 8, 1939.The circuit is closed between the contact ring and an arm of the slacktake up device hence it is of the utmost importance that both of theseelements are kept constantly automatically clean. However, one of thegreatest causes of failure to promptly close the circuit is dirt. Flossfrom the yarn, dust in the machine shop and paraffin in the yarn combineto coat the parts of the machine with an insulating layer which at timesis so thick that it can be scraped olf. The operators have neither thetime nor the inclination to continually wipe these parts to keep themclean. Some means are therefore required whereby the ring and the arm ofthese devices may be automatically selfcleaning.

The object of this invention is to provide an electric contact ring ofnovel design and construction which is practically selfcleaning both foritself and for the wire arm and insures prompt good electric contact. Itmay be stated here that the terms electric contact ring, or contact ringor electric ring are used in the trade to designate the same element towhich this invention relates. In the accompanying drawing- Fig. 1 is adiagrammatic illustration of a stop mechanism for a knitting machineincluding a contact ring according to this invention.

Fig. 2 shows a portion of the ring.

Fig. 3 is a sectional view of the ring taken on line 3-3 of Fig. 2.

Fig. 4 shows the use of the ring in inverted position.

Fig. 5 is a perspective view of another form of ring.

Figs. 6, 7 and 8 show modifications.

Fig. 1 shows a stationary electric stop mechanism for knitting machinessometimes called a knitting machine top. Its use and the manner in whichit is attached to the machine are well Brook yn, N. Y., assignor tocorporation of New 1940, Serial No.- 3328, 252

(Cl. Go -1 63) known in the art. The device comprises a central shaft 1which at the top carries knot detectors 2 which may be of the type shownin the Reissue Patent 19,069, Feb. 6, 1934. Further down and shaftcarries end detectors 3 which may be of the type shown in the Patent1,784,560, Dec, 9, 1930. The yarn bobbins 4 are'supported on arms 5. Theyarn passes up through the end detectors 3, the knot detectors 2 andthen down again through a plate 6 having eyes I for the passage of theyarn Hi.

The contact ring 8 according to this invention is carried by arms 9secured to the shaft. The ringis insulated as indicated at 19. Below thering 8 there is a bracket H, secured to the shaft which supports. slacktake up devices each of which consists of an arm 12 with eyelet l3 and awire spring arm 14 with an eyelet 15. The yarn 16 passes from the plate6 down through the two eyelets l3 and I5 and thence to the knittingmechanism itself, not shown.

Electric current is supplied to the detector devices and the contactring in any suitable and well known manner, wires being indicated at H.The current to the ring is by way of a spring contact finger 18. Theother side of the circuit is grounded on the machine. The circuit isnormally open at 2 and 3 and also at M, the slack take up device beinginsulated from the bracket H as indicated at 20. When the yarn breaks orruns out the wire spring l4 Snaps upward into engagement with the ring.The circuit is then closed and in usual manner the machine stops. Nospecial discussion of the operation of the detectordevices is necessary.They are in daily use and well known to the art.

Heretofore much trouble has arisen from the fact that the contact ringas well as the wires 14 became coated with an insulating layer of dirtand grease so good electric contact could not be had between theseparts. Particularly the wire arms were not scraped clean by merelyengaging the lower edge of a plain rin With a contact ring constructedaccording to this invention such trouble is eliminated. As shown in thedrawing the ring 8 is not a usual ring formed from a plain strip ofconducting metal which provides only a lower straight edge. The ring 8is of V-shape in cross section and provided with teeth 21 whichpreferably are shaped and. spaced as shown in Fig. 2. The teeth haveinwardly sloping surfaces 22 leading to a restricted channel 23 which inturn leads into an enlarged space 24. Preferably the channel is made ofless width than the diameter of the wire arm l4 so that when the lattersnaps up into engagement with the ring, the particles of dirt which arescraped off or become loosened may be thrown into the larger space 24,the wire being caught by the channel. Thus packing or accumulation ofdirt is to some extent prevented or at least delayed. However, the mainfeature of the ring is that the space between the teeth provides foursloping surfaces 22 and if the wire snaps through the channels and intothe spaces 24, the sides of the wire have necessarily been scraped notonly at four different points but at four different areas becauseseldom, if ever, do the wires snap straight upward right into the middleof the spaces between the teeth, This is because the wires are notstationary except relative to their immediate support. They sway andvibrate with the machine and respond to the uneven pull of the yarn. Atno time therefore will rubbing contact between the sides of the teethand the wire occur at the same spot in the wire but the scraping occursalong and across the wire. The upper edges of the ring 26 and 27 arestraight and provide double contact points for the current feedingfinger i 8, The latter is looped and springy to provide contact. Bracesas at 25 may be used to stifien the ring.

Fig. shows a V-shaped ring having straight comb teeth 39. Thisconstruction also provides a plurality of scraping surfaces 3| spacedalong and across the ring. Figs. 6 and 7 show rings which are formedfrom a plain ring band 32 having teeth 33 and 34 shaped somewhat likethose in Fi 2. The sloping surfaces at 35 in the two figures providescraping contacts with the wires M.

The ring may be used inverted as shown in Fig, 4. This figureillustrates a simple type of -vided with spaced teeth end detector. Theswitch arm is held in normal open position by gravity. When the yarnbreaks or runs out, the arm falls forward into engagement with the ringand closes the circuit.

The ring 8 as above described may be. used in both stationary and rotaryknitting machines. Where for some reason the contact finger I8 mustengage the ring from below the teeth may be curved as shown at 36 inFig. 8. The finger will then be wide enough to span several teeth.

With a ring constructed according to this invention it has been foundthat the contacting wire and the ring are kept automatically clean allthe time and the dirt does not accumulate.

I claim:

1. An electric contact ring for knitting machines consisting of a ringbody V-shaped in cross section, spaced teeth formed in the lower edge ofsaid ring, each side of said V-shaped ring forming an upper straightedge and braces secured between the sides of said ring to stiffen thesame.

2. In an electric contacting device for knitting machines including acontact ring and a wire member normally urged into contacting engagementwith said ring to close an electric circuit, said wire member being heldin normal circuit open position by a travelling yarn, said contact ringbeing of V-shaped cross section and proat its lower edge forming narrowentrance channels for said wire member to pass through into the space atthe root of the teeth to contact said ring at several points when saidyarn breaks or runs out whereby to provide good rubbing contact betweensaid wire member and the teeth to make the same selfcleaning for thepurpose described.

MICHAEL WACI-ISMAN.

